It is known in the field of injection molding plastic material to melt, mix and otherwise process plastic by feeding solid plastic such as in granular form through a hopper to the flight of a screw rotating in a barrel. In the usual course of events the screw flights are appropriately dimensioned to melt the solid plastic and to otherwise process and pump the melted material toward an outlet which may be connected to the cavity of a mold. Such a machine is shown in U.S. Pat. No. 3596326 in which a screw is rotated to plasticate and otherwise process plastic material. The flights of this screw as noted above have various configurations to perform different operations and in length may be more than twenty times the diameter of the screw.
It is common for the last stages of the screw to force the melted material past a non-return valve to a collection chamber at the outlet end of the barrel containing the screw. As the material collects, the screw is forced axially backward, therebeing a suitable shut-off valve at the outlet. When an amount of plastic has collected sufficient to fill the mold cavity, rotation of the screw is stopped, the outlet valve is opened and the screw is moved forward to force the melted material into the mold cavity where the material is cooled or otherwise reacted to solidify in the cavity to form a desired article. As should be apparent the length of the screw needed to perform the desired operations to plasticate and process the material as well as the length of machine needed to accommodate the reciprocation of the screw dictates that such reciprocating screw injection molding machines be of considerable length.
There has been recently developed by the Farrel Division of USM Corporation an apparatus known as the DISKPACK Processor for processing plastic material with greater efficiency than the screw of an extruder or injection molding machine. Such an apparatus is typically shown and described in U.S. Pat. Nos. 4142805, 4329065 and 4227816. These patents show a multi-stage rotary processor for plastic and polymeric materials which are or become in the course of processing viscous liquids. An annular housing rotatably receives a rotor having in its cylindrical surface a plurality of annular channels forming with the close fitting housing a plurality of processing passages. Transfer passages conduct the material from passage to passage after processing and finally to a relatively narrow and deep channel which provides pumping pressure to force the processed material from an outlet which may be a die for shape extrusion or which may conduct the material for further processing in another device. It is known that considerable energy is expended in the narrow pumping channels of the DISKPACK Processor.